FMEA – Probability of Detection

Probability of detecting a failure if it has occurred.

• DFMEA
• PFMEA
• FMEA-MSR
• Useful links to sites

The definition varies for different types of FMEA analysis. Therefore, it is necessary to specify the type of analytical process (for individual failures or for properties).

The following overview is based on the automotive industry standard. Before using, check whether it is relevant for your case!

DFMEA

1. Level 1: It is known that the design cannot fail
2. Level 2: Verified standard procedures, aging control
3. Level 3: Verified standard procedures, failure test
4. Level 4: Verified standard procedures, function pass test
5. Level 5: Verified standard procedures in the late development phase, aging control
6. Level 6: Verified standard procedures in the late development phase, failure test
7. Level 7: Verified standard procedures in the late development phase, low, function pass test
8. Level 8: New test procedures are used, which are not verified
9. Level 9: Known tests are not specifically designed to verify potential failures
10. Level 10: Test procedures have not yet been developed

PFMEA

1. Level 1: Failure is virtually impossible or cannot go undetected
2. Level 2: Proven reliable detection methods; machine inspections prevent the occurrence of defective products
3. Level 3: Proven detection methods; defective products are automatically detected
4. Level 4: Proven detection methods; reliable inspections detect the problem during production and reject defective products
5. Level 5: Verified inspections; semi-automatic detection alerts the operator
6. Level 6: Verified inspections; manual inspection of products or samples detects defects
7. Level 7: Unverified inspections; semi-automatic detection alerts the operator
8. Level 8: Unverified inspections depend on manual inspection of products or samples to detect defects
9. Level 9: It is unlikely that inspections will detect the problem; sample checks may not easily identify the issue
10. Level 10: It is unlikely or impossible to detect the issue through inspections

FMEA-MSR

1. Level 1: Always detected – significantly more than 99.9%; the system responds to failures
2. Level 2: Detected with probability > 99.9%, the system is very likely to identify the failure
3. Level 3: Automatic detection identifies failures with probability > 99% with a short response time, automatic reaction is highly probable
4. Level 4: Detection with probability > 97% with medium response variability; the system will usually react to failures
5. Level 5: Detection with probability 90–97%, with moderate response variability; the system will usually respond automatically to failures
6. Level 6: The failure is detected by the user or system with probability > 90% and will likely be able to respond
7. Level 7: Low probability that the user will recognize and respond; diagnostics reveal the problem with >60% accuracy.
8. Level 8: Rarely possible to detect the problem, diagnostics detect failure with < 60% accuracy; user may not always respond
9. Level 9: Failure will almost never be detected; system or user response cannot be relied upon
10. Level 10: Cannot be detected; no response during operation

Useful links to sites

• FMEA Severity Rating
• FMEA Occurrence Rating
• About FMEA in general